66 



THE INDIAN ECLIPSE, 1898. 



connected together by cross-beams, and enclosing a space 12 ft. 

 square, in which the instruments were placed. The roof of the 

 hut was removable, and the sides, which were constructed of 

 light bamboo matting, could be easily adjusted so as to admit 

 or exclude light at any point. 



The disposition of the instruments in the hut is shown in 

 the plan. The prismatic camera was screwed to two wooden 

 posts driven into the ground and bedded in cement. The long 

 axis of the instrument had to be carefully adjusted in azimuth 



PC 



E EcpiaULontiL Tele/- Spectroscope 

 H Hetiastat 

 P.C. PriAmattc Camera, 

 S. S. Stilt, Spectrcgrapih, 

 *7u 8Cr ' Sm-kss Spectrcgraph> &,6 ^Telescope 



GROUND PLAN OF MR. EVERSHED'S OBSERVING HUT. 



and altitude, so that the refracting edges of the prisms should 

 be parallel to a line drawn tangent to the sun's edge at the 

 points of second and third contact. Otherwise the bright lines 

 of the flash spectrum would not be at right angles to the length 

 of the spectrum. A light metal exposing cap was fitted in front 

 of the prisms, which could be easily detached and replaced 

 without causing the slightest tremor. 



The slit spectrograph was arranged in a north and south line, 

 with the collimator and image-forming lens directed towards 

 one of the mirrors of the heliostat. A blackened metal disc 



